Chewing gums, including pellet chewing gums, are frequently enclosed with hard or soft coatings. Coatings provide an opportunity for the manufacturer to vary product characteristics such as taste, appearance and nutritional value. In recent years, efforts have been devoted to producing sugarless hard coatings for use in chewing gum. Sugarless coatings which have been investigated include coatings containing compounds such as xylitol, sorbitol, mannitol, and hydrogenated starch hydrolysates.
U.S. Pat. No. 4,792,453, which is assigned to the same owner as the present application, discloses a chewing gum having a sugarless chewing gum center coated with a syrup containing hydrogenated isomaltulose. The sugarless center may include various substituents such as water, an insoluble gum base, a bulking agent, a softener, an artificial sweetener, and a flavoring agent. The sugarless chewing gum center of the reference has a water content of less than about 2.5 weight percent, preferably less than about 1.5 weight percent and most preferably less than about 1.0 weight percent. The use of a center having a low water content, is intended to prevent or reduce the tendency of the gum center from being a water donor to the hard coating.
Sugarless gums coated with hydrogenated isomaltulose-containing syrup possess excellent appearance, taste, texture, mouth feel, and other desirable properties of hard coated chewing gums. Also, it has been found that the relatively anhydrous gum center has the capability of pulling moisture from the hydrogenated isomaltulose-containing coating, causing the coating to exhibit superior hardness. This moisture-pulling from the gum center is attributable, in large part, to the use of glycerin as a softener in the gum center. The moisture-pulling effect is the most pronounced in hard coated chewing gums which contain moderate or relatively high amounts of glycerin in the chewing gum center, on the order of about 5 to about 15 percent by weight of the chewing gum center.
The tendency of glycerin to pull moisture from the hydrogenated isomaltulose-containing coating can operate as a disadvantage in certain pellet-shaped hard coated chewing gums which, due to their shape, are difficult to isolate from a moisture-containing environment by packaging. For example, pellet gum which is shaped like pillows is difficult to protect from moisture because it is difficult to form a good quality, low or non-moisture permeable package which is suitable for these pellets.
Hydrogenated isomaltulose is a monohydrate. If the hydrogenated isomaltulose-containing coating on the pellet gum becomes too dry, e.g. due to the presence of glycerin, the coating becomes more hygroscopic and begins to absorb moisture from the surrounding atmosphere. This continuous drying and absorption of moisture from the atmosphere, reduces the shelf life of the pellet gum by causing the coating to soften and lose its desirable texture, appearance and mouth feel. Thus, the coating itself must be sufficiently shelf stable against moisture absorption so as not to allow the coating to deteriorate during its shelf life.